With a multidisciplinary approach using methods of clinical ophthalmology, experimental and diagnostic pathology including (1) detailed ophthalmologic examination, fundus photography, fluorescein and cardiogreen angiography; (2) histopathology including freeze-drying techniques, microanatomic dissections and flat preparations; (3) electron microscopy and electron microscopic histochemistry and; (4) experimental animal surgery, we propose to study retinal dysfunctions, in particular, macular degeneration at the clinical, histologic and ultrastructural levels. Human surgical and autopsy materials and experimental animal models will be employed: 1. We will examine macular degeneration based on histopathologic study of 200 cases of diseases of the macula currently on file at the Registry of Ophthalmic Pathology. The morphologic findings will be correlated with available clinical data. 2. We will investigate the role of radiant energy, particularly sungazing, in causation of photic maculopathy in human volunteers. These patients will be studied by clinical ophthalmologic methods and the eyes will be examined by histopathology and electron microscopy. 3. We propose to use freeze-drying technique to study the histopathologic distribution of fuorescein in human subjects so as to improve the interpretation of various fluorescein angiographic patterns in diseases of the posterior pole. 4. We propose to study macular edema in various experimental animal models including breakdown of retinal capillary barrier or RPE-choroidal barrier. These experimental models of rhesus monkeys will be studied by fluorescein angiography clinically. The leakage of fluorescein will be studied histologically by freeze-drying techniques. Horseradish peroxidase will be used as a tracer to study the leakage of these vascular barriers at the ultrastructural levels. The reparative process of macular edema will be assessed.